OMAPFB: Fix possible null pointer dereferencing

Commit 952cbaa (OMAPFB: Change
dssdev->manager references) added checks for OMAPFB_WAITFORVSYNC ioctl
to verify that the display, output and overlay manager exist. However,
the code erroneously uses && for each part, which means that
OMAPFB_WAITFORVSYNC may crash the kernel if no display, output or
manager is associated with the framebuffer.

This patch fixes the issue by using ||.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/omapfb/omapfb-ioctl.c

@@ -787,7 +787,7 @@ int omapfb_ioctl(struct fb_info *fbi, unsigned int cmd, unsigned long arg)
 
 	case OMAPFB_WAITFORVSYNC:
 		DBG("ioctl WAITFORVSYNC\n");
-		if (!display && !display->output && !display->output->manager) {
+		if (!display || !display->output || !display->output->manager) {
 			r = -EINVAL;
 			break;
 		}